Computer system, graphics processing unit, and graphics processing method thereof that are capable of switching different rendering modes

ABSTRACT

A graphics processing unit (GPU) is provided. The GPU includes a command stream parser (CSP) including a profiling unit used to provide performance statistics data for the GPU to determine a rendering mode of the GPU, wherein the rendering mode includes a first rendering mode and a second rendering mode for performing a graphics rendering pipeline for graphics processing. The profiling unit calculates drawing time of frames and the number of objects in the frames when the GPU operates in the first rendering mode, and determines whether the operation of the GPU is switched to the second rendering mode according to the calculated drawing time and the number of objects; when determining that the calculated drawing time and the number of objects are less than their respective thresholds, the CSP causes the operation of the GPU to switch from the first rendering mode to the second rendering mode.

CROSS REFERENCE TO RELATED APPLICATIONS

This application claims priority to Chinese Patent Application No.201811042673.8 filed on Sep. 7, 2018 in the China Intellectual PropertyOffice, the contents of which are incorporated by reference herein. Thepresent application also includes subject matter that is related toco-pending application Ser. No. 16/249,073, filed Jan. 16, 2019.

BACKGROUND OF THE INVENTION Field of the Invention

Aspects of the present invention relate generally to a graphicsprocessing unit, and more particularly, to a computer system, a graphicsprocessing unit, and a graphics processing method thereof that arecapable of switching different rendering modes to reduce powerconsumption.

Description of the Related Art

A graphics processing unit (GPU) is a fairly important operationalcomponent. In general, the power consumption of the GPU is very high, soit is necessary to minimize the power consumption to extend the use timeof the electronic device. The command stream parser used in current GPUswill only use a single rendering mode, so that each stage in thegraphics rendering pipeline needs to render each primitive one by one.For some temporary data of pixels, such as color/depth/stencil data,when the space of the built-in buffer or cache memory on the graphicsprocessing chip is insufficient to store the temporary data of pixels,the temporary data of pixels needs to be written to the memory and thenread back when rendering subsequent primitives to perform operations ofthe subsequent graphics rendering pipeline such as blend/depthtesting/stencil testing. However, when the temporary data of pixelswritten to the memory would be replaced by data of pixels in subsequentprimitives, the write/read operations may waste memory access resources.It results in high power consumption and additional cost.

In addition, since the rendering result of the subsequent primitive maybe affected by the current primitive, each processing stage in thegraphics rendering pipeline in the GPU with the conventional CSP onlycan process a single primitive at a time, resulting the graphicsprocessing performance is not good. Therefore, a graphics processingunit and a graphics processing method thereof capable of supporting highperformance requirements and reducing power consumption are provided inthe present invention to solve the disadvantages.

BRIEF SUMMARY OF THE INVENTION

In a preferred embodiment, the invention is directed to a graphicsprocessing unit (GPU). The GPU comprises a command stream parser (CSP)including a profiling unit used to provide performance statistics datafor the GPU to determine a rendering mode of the GPU, wherein therendering mode includes a first rendering mode and a second renderingmode for performing a graphics rendering pipeline for graphicsprocessing. The profiling unit of the CSP calculates drawing time of aplurality of consecutive frames and the number of graphics objects inthe consecutive frames for a specific application when the GPU operatesin the first rendering mode, and determines whether the operation of theGPU is switched to the second rendering mode according to the calculateddrawing time of the frames and the number of graphics objects in theframes; when determining that the calculated drawing time of the framesand the number of graphics objects in the frames are less than theirrespective thresholds, the CSP causes the operation of the GPU to switchfrom the first rendering mode to the second rendering mode.

In a preferred embodiment, the invention is directed to a graphicsprocessing method, used in a graphics processing unit (GPU), wherein theGPU comprises a command stream parser (CSP) having a profiling unit, andthe GPU supporting a first rendering mode and a second rendering modeperforms a graphics rendering pipeline for graphics processing. Themethod comprises: operating the GPU to be run in the first renderingmode; calculating drawing time of a plurality of consecutive frames andthe number of graphics objects in the consecutive frames of a specificapplication by the profiling unit; and determining whether an operationof the GPU is switched to the second rendering mode according to thecalculated drawing time of the frames and the number of graphics objectsin the frames, wherein when determining that the calculated drawing timeof the frames and the number of graphics objects in the frames are lessthan their respective thresholds, the operation of the GPU is switchedfrom the first rendering mode to the second rendering mode.

In a preferred embodiment, the invention is directed to a computersystem. The computer system comprises a central processing unit (CPU)and a graphics processing unit (GPU). The CPU executes a display driver.The GPU performs a graphics rendering pipeline through a first renderingmode and a second rendering mode and at least comprises a command streamparser (CSP). The CSP includes a profiling unit used to provideperformance statistics data for the GPU to determine a rendering mode ofthe GPU. The profiling unit of the CSP calculates drawing time of aplurality of consecutive frames and the number of graphics objects inthe consecutive frames of a specific application when the GPU operatesin the first rendering mode, and determines whether the operation of theGPU is switched to the second rendering mode according to the calculateddrawing time of the frames and the number of graphics objects in theframes; when determining that the calculated drawing time of the framesand the number of graphics objects in the frames are less than theirrespective thresholds, the CSP triggers the operation of the GPU toswitch from the first rendering mode to the second rendering mode. Theprofiling unit of the CSP calculates a memory flow of the consecutiveframes after the operation of the GPU is switched from the firstrendering mode to the second rendering mode; when a difference betweenthe memory flow and a previous memory flow is greater than apredetermined threshold, the CSP maintains that the GPU operates in thesecond rendering mode; and when the difference between the memory flowand the previous memory flow is not greater than the predeterminedthreshold, the CSP switches to the first rendering mode from the secondrendering mode if the GPU operates in the second rendering mode.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a block diagram illustrating a computer system according toone embodiment of the present invention.

FIG. 2 is a block diagram illustrating the CSP according to oneembodiment of the present invention.

FIG. 3 is a schematic diagram illustrating a command list according toone embodiment of the present invention.

FIG. 4 is a flow chart illustrating a graphics processing methodaccording to an embodiment of the present invention.

FIG. 5 is a flow chart illustrating a graphics processing methodaccording to another embodiment of the present invention.

DETAILED DESCRIPTION OF THE INVENTION

The following description is of the best-contemplated mode of carryingout the invention. This description is made for the purpose ofillustrating the general principles of the invention and should not betaken in a limiting sense. The scope of the invention is best determinedby reference to the appended claims.

It will be further understood that the terms “comprises,” “comprising,”“includes” and/or “including,” when used herein, specify the presence ofstated features, integers, steps, operations, elements, and/orcomponents, but do not preclude the presence or addition of one or moreother features, integers, steps, operations, elements, components,and/or groups thereof.

Use of ordinal terms such as “first”, “second”, “third”, etc., in theclaims to modify a claim element does not by itself connote anypriority, precedence, or order of one claim element over another or thetemporal order in which acts of a method are performed, but are usedmerely as labels to distinguish one claim element having a certain namefrom another element having the same name (but for use of the ordinalterm) to distinguish the claim elements.

FIG. 1 is a block diagram illustrating a computer system according toone embodiment of the present invention. As shown in FIG. 1, thecomputer system 100 comprises a central processing unit (CPU) 110 and agraphics processing unit (GPU) 120, wherein the display driver 111executed by the GPU 120 and the CPU 110 can support, for example, theOpenGL ES standard. The GPU 120 includes a command stream parser (CSP)130, an input assembler 140, a vertex shader 150, a geometry shader 160,and a rasterizer 170, a pixel shader 180, an output merger 190, a memoryresource 200, and an instruction cache 210, wherein the input assembler140, the vertex shader 150, the geometry shader 160, the rasterizer 170,the pixel shader 180, and the output merger 190 are also referred asprocessing stages of a graphics rendering pipeline and compose togethera graphics rendering pipeline. The CSP 130 in the GPU 120 receivesdrawing commands from the display driver 111 executed by the CPU 110 ofthe computer system 100. The CSP 130 transmits the drawing commandsdirectly to subsequent processing stages 140˜190 for processing variousoperations of the graphics rendering pipeline, such as rasterization,depth test, stencil test, and so on. In another embodiment, the CSP 130and the input assembler 140 can be integrated into a single CSP. Itshould be understood that the components within the graphics renderingpipeline may vary from system to system and may be presented in avariety of different manners, and it should not be limited in theinvention. The composition of the graphics rendering pipeline in FIG. 1is well known to those skilled in the art, so only a simplifieddescription is given below and the details related to the graphicsrendering pipeline will be omitted.

The CSP 130 reads command data from the memory resource 200 and performscommand parsing, wherein the memory resource 200 may be a virtual memoryor memories of the GPU 120 and the computer system 100. Then, the CSP130 inputs relevant command parameters of the drawing commands to theinput assembler 140. The input assembler 140 receives the relevantcommand parameters, obtains index values and vertex stream data, andcombines and transmits the index values and the vertex stream data tothe vertex shader 150 and the geometry shader 160. The index value andthe vertex stream data contain actual geometric data, such as vertexidentifier (vertex ID), primitive ID and instance ID, etc., which can beused to adjust procedures or source data by each processing stage of thegraphics rendering pipeline. The input assembler 140 uses differentforms of primitives, such as line lists and triangle strips, toconstruct actual triangles. The vertex shader 150 processes vertex dataand uses the vertex data to construct triangles and polygons of anobject to be displayed to perform operations such as transformation,skinning, lighting and so on. The geometry shader 160 may receivevertices processed through the transformation, skinning, and lighting,and generates new vertex data after processing. The drawing data afterthe shading processing described above is transmitted to the rasterizer170 for rasterization. The rasterizer 170 performs perspective divide,clipping, and viewport/scissor selection and implementation, andproduces color information of all pixels of the outputted primitives tothe pixel shader 180 to provide an early visibility test. The pixelshader 180 can perform pixel shading on the rasterized drawing data,processes each pixel and changes the color value of each pixel accordingto various color characteristics (for example, functions of a reflectionvalue or a mirrored color value and a transparent value may bedetermined according to the position of the light source and the normalvector of the vertex), and outputs the result after color processing tothe output merger 190. The output merger 190 is a fixed function unit,and is also generally the final stage in the graphics rendering pipelineprocess, wherein the function of the output merger 190 is to take all ofthe results generated by the graphics rendering pipeline process andmerge the results into the final pixel value that are seen on thescreen. The output merger 190 may use stencil values, depth values alongwith multiple rendering targets along with various blending functions tocreate a rendering target to be displayed. The display data after theblending process can be further written into a display memory by a cachememory (not shown in FIG. 1) via a memory access unit (not shown in FIG.1).

In the architecture of the GPU 120 in FIG. 1, the CSP 130 of the presentinvention, which is different from the traditional CSP only operating ina single rendering mode, may operate in two different rendering modes,that is, the first rendering mode and the second rendering mode.Specifically, the first rendering mode may be an immediate renderingmode (IMR mode), while the second rendering mode may be a tile renderingmode (TBR mode). In the immediate rendering mode, the GPU 120 rendersthe entire rendering target in units of primitives. In the tilerendering mode, the CSP 130 may divide the entire rendering target intoa plurality of tiles, and then may render the rendering target in unitsof tiles, wherein the size and pixel coordinates of the tiles arepredefined. In the tile rendering mode, each of the processing stages140˜190 in the three-dimensional graphics rendering pipeline of the GPU120 renders the predefined tiles and uses a scissor (not shown inFIG. 1) to indicates related information of a current tile, such as thesize of the tile, the coordinates in the entire rendering target, etc.,wherein the related information of the current tile is provided for eachof the processing stages 140˜190 to perform the rendering operationsdescribed above. For example, the size of the tile can be 8×8, 16×16pixels, and the like. Alternatively, the CSP 130 may also transmit acontrol signal to the CPU 110 to indicate that a rendering mode which ismore suitable for the current application.

FIG. 2 is a block diagram illustrating the CSP 130 according to oneembodiment of the present invention. The CSP 130 comprises at least aregister pool 131, a profiling unit 132, a pre-fetch buffer 133, apre-parsing unit 134, a main parsing unit 135, and an input assembler136. The CSP 130 is also coupled to the bus interface unit (BIU) 220 andis coupled to the memory resource 200 via the instruction cache 210.

The register pool 131 stores related register data for the CSP 130 sentby the BIU 220. The profiling unit 132 performs performance analysis onthe graphics processing of the GPU, generates performance analysisresults, and sends a control signal, such as an interrupt signal, to theCPU 110 via the BIU 220 according to the performance analysis results toinstruct the CPU 110 to switch the rendering mode of the GPU 120 in theFIG. 1. A plurality of counters are defined in the profiling unit 132for counting graphics processing performances of the processing stages140˜190 of the GPU 120 of FIG. 1. In an embodiment, the statisticsincludes the time required for drawing a frame. In another embodiment,the statistics includes the number of all objects drawn in a frame. Inyet another embodiment, the statistics includes statistical memorytraffic, and so on, wherein the statistical memory traffic is the numberof reads and writes in the memory. The profiling unit 132 can performstatistical analysis on various types of applications and establish athreshold corresponding to each counter in advance. The profiling unit132 or the graphics driver (not shown in FIG. 2) can query and calculatestatistics data of the performance analysis (such as a drawing time andthe number of objects in consecutive frames of a specific application)by specific commands, and transmits a command of the suitable renderingmode to the CPU 110 of FIG. 1 according to the statistics data. The CPU110 instructs the GPU 120 to flexibly switch the rendering modeaccording to the command. That is, for each application, the CSP 130 canprovide hints for suitable rendering modes to the CPU 110 according tovarious performance analysis results provided by the profiling unit 132,and the CPU 110 can switch the rendering mode used by the GPU 120according to the hints provided from the CSP 130 such that the CSP 130may switch to the corresponding rendering mode. The details of switchingthe rendering modes are shown in the description of FIG. 5.

The pre-fetch buffer 133 is used to buffer a small amount of commandsand indirect data used for the pre-parsing unit 134 and the main parsingunit 135. When the rendering mode is the first rendering mode, thepre-fetch buffer 133 directly sends a read request to the memoryresource 200 to fetch the data back from the memory resource 200 to thepre-fetch buffer 133 directly. When the rendering mode is the secondrendering mode, the pre-fetch buffer 133 accesses the read request fromthe memory resource 200 and fetches the data via the instruction cache210.

The pre-parsing unit 134 is used to pre-parse all the commands in acommand list to parse the indirect data included in the commands andperform pre-fetching of the indirect data. The main parsing unit 135 isused to perform complete parsing on each command, and send the parseddata to each corresponding unit subsequent to the graphics renderingpipeline, such as the input assembler 140, the vertex shader 150 in theFIG. 1, and so on. It should be noted that, in some embodiments, thepre-parsing unit 134 and the main parsing unit 135 may also beintegrated into a single parsing unit. The input assembler 136 cancombine the vertex data into several different primitive types andoutputs the data (such as register data, commands, vertex data, etc.) tosubsequent processing stages 140˜190 of the graphics rendering pipeline.

In addition, in the second rendering mode, since all the commands needto be parsed for each tile, an instruction cache 210 is furtherconfigured in the GPU 120 of FIG. 1 in the present invention to store acommand list performed for all tiles in each frame and the indirect dataof the commands in the command list. In an embodiment, a space may beconfigured on the original system cache, such as the L2 cache, as theinstruction cache 210. The instruction cache 210 is reserved for use ofthe second rendering mode to speed up the graphics processing. Theinstruction cache 210 can be further divided into a non-replaceablecache and a replaceable cache. The non-replaceable cache can be furtherdivided into a static data cache and a dynamic data cache. The staticdata cache is mainly used to store the command list for each tile. Thecontent in the static data cache is fixed after the first allocation iscompleted. It means that the replacement cannot be performed until allthe tiles of the current frame are completed, and the content in thestatic data cache is unpinned or invalid after the rendering of thecurrent frame is completed. The dynamic data cache is mainly used tostore the indirect data for each command. The indirect data is data thatcannot be directly obtained from the command list, such as commands thatuse indirect addresses. Since the indirect data may be updated by theCPU 110, the indirect data should be updated synchronously to theinstruction cache 210 when the indirect data is updated. A cacheinvalidation command can be used in the GPU 120 to achievesynchronization. When the CSP 130 needs to read the data from thedynamic data cache again after the invalidation, the dynamic data cachemay load the data from the memory resource 200 and then transmits thedata back to the CSP 130.

The replaceable cache is configured with a spare space, and theavailable space in the replaceable cache can be used by a static datacache and a dynamic data cache freely. Since the sizes of the commandlists and the indirect data between each frame of each application maybe different, the size of the space configured in the non-replaceablecache may not be sufficient for processing some frames. Therefore, theCSP 130 can store/configure data beyond the portion of thenon-replaceable cache in the spare space of the replaceable cache.

Specifically, the display driver 111 executed by the CPU 110 determineswhether the rendering mode of the GPU 120 is the second rendering mode.When the display driver 111 determines that the rendering mode of theGPU 120 is the second rendering mode, the display driver 111 executed bythe CPU 110 inserts a specific command stream parsing (CSP) command foreach frame in the original command list. Specifically, the specific CSPcommand may include at least a frame-begin instruction command and aframe-end instruction command, wherein the display driver 111 insertsthe frame-begin instruction command prior to the start of the commandlist of each frame, inserts the frame-end instruction command after theend of each frame and transmits the command list of each frame to theGPU 120. FIG. 3 is a schematic diagram illustrating a command listaccording to one embodiment of the present invention. As shown in FIG.3, the command list 300 includes a plurality of drawing commands,wherein the command list of the n^(th) frame is 310. The display driver111 inserts a frame-begin instruction command “Frame_begin”311 prior tothe start of the command list of the n^(th) frame 310 and inserts aframe-end instruction command “Frame_end”312 after the end of the frame.Then, the display driver 111 transmits the command list with theframe-begin instruction command “Frame_begin”311 inserted prior to thestart of the frame and the frame-end instruction command “Frame_end”312inserted after the end of the frame to the GPU 120. When the CSP 130receives the command list including multiple drawing commands from thedisplay driver 111, the CSP 130 parses the command list to obtain andtransmit the command list including the frame-begin instruction command“Frame_begin”311 and the frame-end instruction command “Frame_end”312 tothe GPU 120. When the CSP 130 receives the command list includingmultiple drawing commands from the display driver 111 and parses thecommand list to obtain the specific CSP commands including theframe-begin instruction command “Frame_begin”311 and the frame-endinstruction command “Frame_end”312, the CSP 130 stores a set of firstcommands (e.g., the command list 310 of the n^(th) frame) between thespecific CSP commands into the instruction cache 210 to prepare forsubsequent execution of graphics processing in the second renderingmode.

FIG. 4 is a flow chart illustrating a graphics processing methodaccording to an embodiment of the present invention. In the embodiment,it is assumed that the GPU 120 initially operates in the first renderingmode, and the first rendering mode is the immediate rendering mode andthe second rendering mode is the tile rendering mode.

In step S410, the CSP 130 in the GPU 120 receives a command list fromthe display driver 111 and parses the commands in the command list.Next, the CSP 130 determines a rendering mode of the GPU 120 accordingto the command parsing result and executes a graphics rendering pipeline(such as the processing stages 140˜190 shown in FIG. 1) in acorresponding rendering mode for graphics processing. Specifically,since the display driver executed by the CPU 110 inserts a specific CSPcommand (such as the “Frame_begin”311 shown in FIG. 3) for each frame inthe original command list when the rendering mode of the GPU 120 is thesecond rendering mode, the CSP 130 can determine whether at least onespecific CSP command is included in the command list to determine therendering mode operated by the GPU 120.

In step S420, the CSP 130 determines whether at least one specific CSPcommand is included in the command list received by the GPU 120 from thedisplay driver 111. For example, the specific CSP commands may be theframe-begin instruction command “Frame_begin”311 and the frame-endinstruction command “Frame_end”312 shown in FIG. 3, which are used toindicate the positions of the start and the end of the commands of eachframe, respectively. When the CSP 130 determines that the specific CSPcommand is not included in the command list (for example, theframe-begin instruction command “Frame_begin”311 is not included in thecommand list) (that is, NO in step S420), in step S430, the CSP 130determines that the rendering mode is the first rendering mode andperforms graphics processing on a graphics target in units ofprimitives.

On the contrary, when the CSP 130 determines that the specific CSPcommand is included in the command list (for example, the frame-begininstruction command “Frame_begin”311 is included in the command list)(that is, Yes in step S420), in step S440, the CSP 130 determines thatthe rendering mode is switched from the first rendering mode to thesecond rendering mode since the GPU 120 initially operates in the firstrendering mode, divides the graphics target into a plurality of tiles,and obtains a plurality of first drawing commands from the command listaccording to the specific CSP command and executes the first drawingcommands for each tile to perform the drawing process.

In an embodiment, at least one specific CSP command includes a firstspecific command and a second specific command, and the CSP 130 fetchesa plurality of command between the first specific command and the secondspecific command in the command list as the first drawing commands. Forexample, refer to FIG. 3, the first specific command is the frame-begininstruction command “Frame_begin”311 and the second specific command isa frame-end instruction command “Frame_end”312, which are used toindicate the start and end of the commands of each frame, respectively.The CSP 130 may parse multiple commands at a time, sets a set ofcommands (for example, the command list 310) between the specific CSPcommands 311 and 312 in the command list as the first drawing commands,and stores the first drawing commands in the instruction cache 210 forperforming subsequent graphics processing in the second rendering mode.In another embodiment, the CSP 130 may parse a command at a time. Whenthe CSP 130 determines that the parsed command is the first specific CSPcommand 311, the CSP 130 stores the subsequent commands to theinstruction cache 210 until the second specific CSP command 312 isparsed, and sets the commands in the instruction cache 210 as the firstdrawing commands, wherein the instruction cache 210 can be furtherdivided into a non-replaceable cache and a replaceable cache. Thenon-replaceable cache is used to store a command list corresponding tothe first drawing commands, and at least one indirect data correspondingto the first drawing commands. In an embodiment, the non-replaceablecache further includes a static data cache and a dynamic data cachewhich are used to store the command list corresponding to the firstdrawing commands and at least one indirect data corresponding to thefirst drawing commands, respectively. Thereafter, the CSP 130 may fetchthe first drawing commands from the instruction cache 210 to performcommand parsing for each of the tiles.

In an embodiment, the first specific instruction further includes tileinformation, and the CSP 130 can determine the number of tiles of eachframe and the coordinate position of each of the tiles according to thetile information, so that the subsequent processing stages (for example,the processing stages 140˜190 shown in FIG. 1) of the graphics renderingpipeline may generate required data such as vertex data, etc.Specifically, the tile information can provide information about thesize of the graphics target (for example, “width” and “height”) andinformation about the size of each tile (for example, “tile_width” and“tile_height”). Therefore, the CSP 130 can calculate the numbers oftiles cut in the horizontal direction and the vertical direction,respectively, according to the information about the size of thegraphics target and the information about the size of each tile todetermine the number of tiles for each frame and the coordinate positionof each of the tiles in the entire rendering target.

Since the GPU 120 only needs to use a small buffer to store therendering result of each tile after the rendering mode is switched tothe second rendering mode and only needs to flush the pixel result ofthe visible area into the memory, the number of memory accesses duringthe graphics processing can be effectively reduced and the powerconsumption can be reduced by less memory accesses. In addition, sincethe tiles cover non-overlapping portions of the rendering target, thetiles can be rendered independently after being split by pixelcoordinates. Therefore, the GPU 120 can also achieve higherthree-dimensional graphics performance in the second rendering mode.

In some embodiments, in the second rendering mode, the CSP 130 mayperform command parsing of the first drawing commands for each tile ofeach frame in sequence and may determine whether the command parsing ofthe first drawing commands is performed only once for some tilesaccording to the command type of each first drawing command. In anembodiment, the CSP 130 determines whether a first drawing commandbelongs to a two-dimensional drawing command. When the CSP 130determines that the first drawing command belongs to a two-dimensional(2D) drawing command, the CSP 130 determines that the first drawingcommand is a predetermined drawing command. When the CSP 130 determinesthat the first drawing command does not belong to a two-dimensionaldrawing command, the CSP 130 determines that the first drawing commandis a three-dimensional (3D) drawing command. When the CSP 130 determinesthat the first drawing command is a predetermined drawing command (i.e.,a two-dimensional drawing command), the CSP 130 performs the commandparsing of the first drawing commands only once for all the tiles of thecurrent frame. Specifically, in the second rendering mode, the CSP 130can receive all the drawing commands of a certain frame from the displaydriver 111 and can determine whether the drawing commands only needs tobe parsed once according to the type of the drawing command. The CSP 130determines whether the type of the drawing command is a general commandor a specific command, and determines whether the command parsing of thesubsequent tiles after the first tile can be skipped according to thedetermination result. In an embodiment, the type of drawing command canbe divided into a three-dimensional drawing command and atwo-dimensional drawing command, wherein the three-dimensional drawingcommand can be regarded as a general command, and the two-dimensionaldrawing command, such as a clear command, a copy command, etc., can beregarded as a specific command. For example, it is assumed that eachframe is divided into 8 blocks #0˜#7. When the drawing command is ageneral command (such as a three-dimensional drawing command), the CSP130 performs the command parsing eight times on the general command torender 8 tiles #0˜#7. When the drawing command is a specific command(such as a two-dimensional drawing command), the CSP 130 only performsthe command parsing on a specific command once to render the first tile#0 and skips the command parsing on the next 7 tiles #1˜#7. In anembodiment, the CSP 130 may add a special skip hint on the specificcommand after the first command parsing is performed, and then the CSP130 may skip the command parsing of subsequent tiles according to thespecial skip hint.

In some embodiments, the CSP 130 may further perform mode switchingbetween the two rendering modes according to the performance analysisresults provided by the profiling unit 132. Specifically, the renderingmode includes at least the first rendering mode (the immediate renderingmode), and the second rendering mode (the tile rendering mode), whereinthe mode switching includes the first rendering mode is switched to thesecond rendering mode, and the second rendering mode is switched to thefirst rendering mode.

FIG. 5 is a flow chart illustrating a graphics processing methodaccording to another embodiment of the present invention. The graphicsprocessing method is used to perform the mode switching between thefirst rendering mode and the second rendering mode according with theperformance analysis results provided by the profiling unit 132 in FIG.2. In the embodiment, it is assumed that the GPU 120 initially operatesin the first rendering mode, wherein the first rendering mode is theimmediate rendering mode and the second rendering mode is the tilerendering mode. In step S510, the CSP 130 in the GPU 120 calculates thedrawing time of a plurality of consecutive frames (for example, fiveconsecutive frames) and the number of objects in the consecutive frames(for example, five consecutive frames) for a certain application throughthe profiling unit 132. In step S520, the CSP 130 determines whether thecalculated time and the number of objects in the consecutive frames areless than corresponding thresholds. Specifically, the CSP 130 determineswhether the calculated drawing time of the consecutive frames is lessthan a predetermined time threshold and whether the number of graphicsobjects is less than a predetermined number threshold. When the drawingtime of the consecutive frames is less than the predetermined timethreshold and the number of objects is less than the predeterminednumber threshold, the CSP 130 determines that the drawing time of theconsecutive frames and the number of objects in the consecutive framesare both less than their respective thresholds. Otherwise, the CSP 130determines that the drawing time of the consecutive frames and thenumber of objects in the consecutive frames are not both less than theirrespective thresholds. When determining that the drawing time of theconsecutive frames and the number of objects in the consecutive framesare not both less than their respective thresholds (No in step S520) (itmeans that the first rendering mode is maintained without beingswitched), the process returns to step S510 and the CSP 130 continuesfetching the drawing time of the consecutive frames and the number ofobjects in the consecutive frames to determine whether the renderingmode needs to be switched.

When determining that the drawing time of the consecutive frames and thenumber of objects in the consecutive frames are both less than theirrespective thresholds (Yes in step S520), in step S530, the CSP 130determines that the operation of the GPU 120 is switched from the firstrendering mode to the second rendering mode. In the embodiment, the CSP130 transmits a control signal (e.g., an interrupt signal) including amode switching hint to the CPU 110 through the profiling unit 132, sothat the CPU 110 switches the operation of the GPU 120 from the firstrendering mode to the second rendering mode.

After the operation of the GPU 120 is switched from the first renderingmode to the second rendering mode, the CSP 130 calculates the memorytraffic through the profiling unit 132 when drawing the consecutiveframes in step S540. In step S550, the CSP 130 determines whether thememory traffic (for example, the number of read/writes of the memory)when drawing the consecutive frames is significantly reduced.Specifically, the CSP 130 determines whether the memory traffic whendrawing the consecutive frames is significantly less than the previouslystored/calculated memory traffic. For example, the CSP 130 determineswhether the difference between the memory traffic when drawingconsecutive frames and the previous memory traffic is greater than apredetermined threshold. When the CSP 130 determines that the differencebetween the memory traffic when drawing consecutive frames and theprevious memory traffic is greater than the predetermined threshold, theCSP 130 determines that the memory traffic when drawing the consecutiveframes is significantly reduced. Otherwise, the CSP 130 determines thatthe memory traffic when drawing the consecutive frames is notsignificantly reduced. For instance, the CSP 130 determines whether thememory traffic when drawing the consecutive frames is less than a halfor a predetermined ratio of the previous memory traffic to determinewhether the difference between the memory traffic when drawing theconsecutive frames and the previous memory traffic is greater than apredetermined threshold.

When the CSP 130 determines that the memory traffic when drawing theconsecutive frames is significantly reduced (YES in step S550) (it meansthat the rendering mode does not need to be switched and the GPU 120maintains to be run in the second rendering mode), the process backs tostep S540, and the CSP 130 obtains the memory traffic when drawing theconsecutive frames and determines whether the rendering mode needs to beswitched.

When the CSP 130 determines that the memory traffic when drawing theconsecutive frames is not significantly reduced (NO in step S550) (itmeans that the performance is deteriorated), in step S560, the CSP 130determines that the operation of the GPU 120 is switched from the secondrendering mode to the first rendering mode. Then, the process returns tostep S510, the CSP 130 re-obtain the drawing time of the consecutiveframes and the number of objects in the consecutive frames, anddetermines whether the rendering mode needs to be switched. In theembodiment, the CSP 130 transmits the control signal including a modeswitching hint (such as an interruption signal) to the CPU 110, so thatthe CPU 110 switches the operation of the GPU 120 from the secondrendering mode back to the first rendering mode for subsequent graphicsprocessing.

In summary, in the present invention provides a computer system, a GPU,and a graphics processing method thereof, providing a CSP supportinghigh performance requirements. The CSP can provide the GPU to supporttwo different rendering modes at the same time, and can flexibly switchbetween the two different rendering modes according to the performanceof the GPU, thereby speeding up the processing speed of the GPU toimprove graphics performance and reduce overall power consumption.

Although the embodiment has been described as having specific elementsin FIGS. 1 to 2, it should be noted that additional elements may beincluded to achieve better performance without departing from the spiritof the invention.

While the disclosure has been described by way of example and in termsof the preferred embodiments, it is to be understood that the disclosureis not limited to the disclosed embodiments. On the contrary, it isintended to cover various modifications and similar arrangements (aswould be apparent to those skilled in the art). Therefore, the scope ofthe appended claims should be accorded the broadest interpretation so asto encompass all such modifications and similar arrangements.

What is claimed is:
 1. A graphics processing unit (GPU), comprising: acommand stream parser (CSP), including a profiling unit used to provideperformance statistics data for the GPU to determine a rendering mode ofthe GPU, wherein the rendering mode includes a first rendering mode anda second rendering mode for performing a graphics rendering pipeline forgraphics processing, wherein the profiling unit of the CSP calculatesdrawing time of a plurality of consecutive frames and the number ofgraphics objects in the consecutive frames for a specific applicationwhen the GPU operates in the first rendering mode, and determineswhether the operation of the GPU is switched to the second renderingmode according to the calculated drawing time of the frames and thenumber of graphics objects in the frames; when determining that thecalculated drawing time of the frames and the number of graphics objectsin the frames are less than their respective thresholds, the CSP causesthe operation of the GPU to switch from the first rendering mode to thesecond rendering mode, wherein the profiling unit of the CSP calculatesa memory flow of the consecutive frames after the operation of the GPUis switched from the first rendering mode to the second rendering mode;when a difference between the memory flow and a previous memory flow isgreater than a predetermined threshold, the CSP maintains that the GPUoperates in the second rendering mode; and when the difference betweenthe memory flow and the previous memory flow is not greater than thepredetermined threshold, the CSP switches to the first rendering modefrom the second rendering mode such that the GPU operates in the secondrendering mode.
 2. The graphics processing unit (GPU) as claimed inclaim 1, wherein the step of determining that the calculated drawingtime of the frames and the number of graphics objects in the frames areless than their respective thresholds further comprising: determiningwhether the drawing time of the frames is less than a predetermined timethreshold and whether the number of graphics objects is less than apredetermined number threshold; determining that the calculated drawingtime of the frames and the number of graphics objects in the frames areless than their respective thresholds when determining that the drawingtime of the frames is less than the predetermined time threshold and thenumber of graphics objects is less than the predetermined numberthreshold; and determining that the calculated drawing time of theframes and the number of graphics objects in the frames are not lessthan their respective thresholds when determining that the drawing timeof the frames is not less than the predetermined time threshold or thenumber of graphics objects is not less than the predetermined numberthreshold.
 3. The graphics processing unit (GPU) as claimed in claim 1,wherein the profiling unit further transmits a control signal to acentral processing unit (CPU) to cause the GPU to perform switchingbetween the first rendering mode and the second rendering mode.
 4. Thegraphics processing unit (GPU) as claimed in claim 1, wherein the firstrendering mode is an immediate rendering mode (IMR mode) and the secondrendering mode is a tile rendering mode (TBR mode).
 5. A graphicsprocessing method, used in the graphics processing unit (GPU), whereinthe GPU comprises a command stream parser (CSP) having a profiling unit,and the GPU supporting a first rendering mode and a second renderingmode performs a graphics rendering pipeline for graphics processing, themethod comprises: operating the GPU to be run in the first renderingmode; calculating drawing time of a plurality of consecutive frames andthe number of graphics objects in the consecutive frames of a specificapplication by the profiling unit; determining whether an operation ofthe GPU is switched to the second rendering mode according to thecalculated drawing time of the frames and the number of graphics objectsin the frames, wherein when determining that the calculated drawing timeof the frames and the number of graphics objects in the frames are lessthan their respective thresholds, the operation of the GPU is switchedfrom the first rendering mode to the second rendering mode; calculatinga memory flow of the consecutive frames by the profiling unit after theoperation of the GPU is switched from the first rendering mode to thesecond rendering mode; maintaining that the GPU operates in the secondrendering mode when the difference between the memory flow and aprevious memory flow is greater than a predetermined threshold; andswitching to the first rendering mode from the second rendering modesuch that the GPU operates in the second rendering mode when thedifference between the memory flow and the previous memory flow is notgreater than the predetermined threshold.
 6. The graphics processingmethod as claimed in claim 5, wherein the step of determining that thecalculated drawing time of the frames and the number of graphics objectsin the frames are less than their respective thresholds furthercomprising: determining whether the drawing time of the frames is lessthan a predetermined time threshold and whether the number of graphicsobjects is less than a predetermined number threshold; determining thatthe calculated drawing time of the frames and the number of graphicsobjects in the frames are less than their respective thresholds whendetermining that the drawing time of the frames is less than thepredetermined time threshold and the number of graphics objects is lessthan the predetermined number threshold; and determining that thecalculated drawing time of the frames and the number of graphics objectsin the frames are not less than their respective thresholds whendetermining that the drawing time of the frames is not less than thepredetermined time threshold or the number of graphics objects is notless than the predetermined number threshold.
 7. The graphics processingmethod as claimed in claim 5, wherein the profiling unit furthertransmits a control signal to a central processing unit (CPU) to causethe GPU to perform switching between the first rendering mode and thesecond rendering mode.
 8. The graphics processing method as claimed inclaim 5, wherein the first rendering mode is an immediate rendering mode(IMR mode) and the second rendering mode is a tile rendering mode (TBRmode).
 9. A computer system, comprising: a central processing unit(CPU), executing a display driver; a graphics processing unit (GPU),performing a graphics rendering pipeline through a first rendering modeand a second rendering mode and at least comprising: a command streamparser (CSP), including a profiling unit used to provide performancestatistics data for the GPU to determine a rendering mode of the GPU,wherein the profiling unit of the CSP calculates drawing time of aplurality of consecutive frames and the number of graphics objects inthe consecutive frames of a specific application when the GPU operatesin the first rendering mode, and determines whether the operation of theGPU is switched to the second rendering mode according to the calculateddrawing time of the frames and the number of graphics objects in theframes; when determining that the calculated drawing time of the framesand the number of graphics objects in the frames are less than theirrespective thresholds, the CSP triggers the operation of the GPU toswitch from the first rendering mode to the second rendering mode,wherein the profiling unit of the CSP calculates a memory flow of theconsecutive frames after the operation of the GPU is switched from thefirst rendering mode to the second rendering mode; when a differencebetween the memory flow and a previous memory flow is greater than apredetermined threshold, the CSP maintains that the GPU operates in thesecond rendering mode; and when the difference between the memory flowand the previous memory flow is not greater than the predeterminedthreshold, the CSP switches to the first rendering mode from the secondrendering mode if the GPU operates in the second rendering mode.